Electric switch or circuit breaker



L. C. HART ELECTRIC SWITCH OR CIRCUIT BREAKER Jan. 22, 1952 5 Sheets-Sheet Filed Aug. 14, 1946 5 26 [R e/Z2 07 +7 leszer Cflari 26 I w 10 I. 2

3 Sheets-Shea L. C. HART ELECTRIC SWITCH OR CIRCUIT BREAKER Jan. 22, 1952 Filed Aug. 14, 1946 Jan. 22, 1952 L. c. HART ELECTRIC SWITCH OR CIRCUIT BREAKER Filed Aug. 14, 1946 fizyeizz or lea fer 67 fiarz Patented in. 22, 1952 2.5mm ELECTRIC swrrcn on cnwurr aasaxaa Lester 0. Hart, Cleveland, Ohio, assignor to Hi- Voltage Equipment Company, Cleveland, Ohio,

a corporation of Ohio Application August 14, 1046, Serial No. 600,882

1 12 Claims.

The present invention relates to electric switches or circuit breakers and more particularly to circuit breakers for use in controlling lighting or moderate power distribution circuits. Circuit breakers for this type of service are subjected to very severe and very exacting operating requirements. The normal current which they must carry is relatively low but the short circuit current which such a switch or circuit breaker may be required to interrupt often reaches very high values due to the fact that other circuits connected to the system feed power to the short circuit controlled by this switch or circuit breaker. Consequently, it is essential that such a circuit breaker must be capable of opening the controlled circuit practically instantaneously upon the occurrence of a short circuit. In order to maintain continuity of service, the circuit breaker must not act to interrupt 'the circuit upon the occurrence of moderate overloads until such overload conditions if permitted to continue would endanger the controlled circuit as well as associated apparatus. In addition to these rather severe operational requirements, a commercially successful breaker or switch of this type must be low in cost due to the large number required even in a moderate sized building or factory and furthermore because such devices compete directly with the generally used fuse and switch combination. Usually this type of breaker is manually operable to the open or closed position. For satisfactory operation, the circuit breaker should be of the "trip free" type. By this is meant that even though the circuit breaker or switch is being moved to the closed position, a short circuit condition on the line controlled by the breaker existing at the instant of closure should be capable of opening the breaker even though the operator continues to move the manual means towards the closed position or holds the manual means so that it is not free to move to the open position.

it is an object of the present invention to provide an improved circuit breaker of the abovementioned type capable of substantially instantly interrupting the circuit in the event of a short circuit condition and yet being simple from a manufacturing standpoint and economical from a cost standpoint.

It is another object of the present invention to provide a new and improved operating mechanism for a circuit breaker oi the above-mentioned type.

Still another object of the present invention is to provide new and improved current respon- 2 sive tripping means for an electric circuit breaker capable of distinguishing between short circuit conditions and long time overload conditions, which will cause instantaneousoperation of the breaker in the event of a short circuit condition or operation of the breaker if an overload condition persists for a predetermined length of time. r

A further object of the present invention is to provide a new and improved arc extinguishing structure for a circuit breaker of the abovementioned type whereby the circuit breaker is capable of interrupting currents of large magnitude without visible flame or the emission of arc gases and without noise.

A still further object of the present invention is to provide a combined thermal-and electro-rcsponsive tripping means of a very sensitive and improved construction.

It is another obiect of the present invention to provide a new and improved arrangement for a multi-pole breaker in which an overload on any pole of the breaker causing tripping of that pole of the breaker will automatically cause operation of the other poles of the breaker.

Further objects and advantages of the present invention will become apparent as the followin description proceeds and the features of novelty which characterize this invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of the present invention, reference may be had to the accompa ying drawings in which:

Fig. l is a perspective view of a single pole switch or circuit breaker embodying the present invention;

Fig. 2 is a longitudinal sectional view of the circuit breaker shown in Fig. 1 to illustrate the operating mechanism and are extinguishing structure thereof with the circuit breaker shown in the closed position;

Fig. 3 is a somewhat simplified semi-schematic view of Fig. 2 showing the circuit breaker in the open position, but with the automatic trip means in the operated condition indicating that the contacts were opened in response to an abnormal current condition on the controlled circult;

Fig. 4 is a view similar to Fig. 3 with the circuit breaker in the open position and with the automatic tripping means in the charged or operative condition;

Fig. 5 is a view similar to Fig. 3 showing the circuit breaker in the closed position substantially as shown in Fig. 2 of the drawings;

Fig. 6 is a sectional view taken on line -6 of of Fig. 2 assumin that Fig. 2 shows a complete structure;

Fig. '7 is a sectional view taken on line of Fig. 2 assuming that Fig. 2 shows a complete structure;

Fig. 8 is a sectional view taken on line 8-4 of Fig. 2 assuming that Fig. 2 shows a complete structure;

Fig. 9 is a sectional view somewhat similar to Fig. 2 of a portion of an electric circuit breaker embodying a modification of the present invention;

Fig. is a perspective view similar to Fig. 1 of a multi-pole breakerembodying a modification of the present invention; and

Fig. 11 is a sectional view similar to Fig. 9 I

taken on line of Fig. 10.

It will be understood from the following description that the present invention is applicable to single pole or multi-pole circuit breakers and although'reference was made above to the fact that circuit breakers of the type with which the present invention is concerned are primarily adapted for low or moderate power circuits, it should be understood that the invention is not necessarily limited to the protection of such circuits and it is not intended that the invention be limited except as indicated in the appended claims.

Referring now to the drawings, there is illustrated an insulated base member l0 preferably formed of molded insulating material of any suitable type which is adapted to cooperate with a suitable cover member II also formed of insulating material preferably molded to the desired shape. The cover H is provided with a suitable opening I2 through which projects the handle I3 of an operating mechanism to be described in greater detail hereinafter. As shown in Fig. 1 of the drawings, the cover II is provided with suitable indicia for indicating the condition of the circuit breaker when the manual operating handle I3 is in certain predetermined positions. Only the on and off positions are indicated in Fig. 1 of the drawings, but as will become apparent from the following description, an additional position of' the operating handle l3 may be indicated to show that the circuit breaker has been opened in response to an abnormal condition on the circuit controlled thereby. This is a desirable feature since it warns the operator that the condition which caused the automatic opening of the circuit breaker may still exist and in certain cases, it may be desirable to investigate and remove such abnormal condition before returning the circuit breaker to the closed position. This will be more clearly pointed out in the following description. The cover II is also provided with notched end portions l4 and I5 to afford access to, the terminals l6 and II, respectively, which are supported at the ends of the base member I0. Suitable fastening means generally indicated at |8 may be provided for holding the cover II and base member III in the unitary relationship shown in Fig. 1 of the drawings. It should be understood that any other suitable means for accomplishing this purpose may be employed.

' As best shown in Fig. 2 of the drawings, the cover II and the base l0 define a chamber or housing for the electric switch or circuit breaker of the present invention which comprises a -pair of relatively movable contacts I5 and 20 controlled by a suitable operating mechanism generally indicated at 2| and positioned in the major portion of the housing defined by the base l0 and the cover II. In order to aid in the extinguishment of an are drawn between the contacts [9 and 20 upon separation thereof, there is provided a suitable arc extinguishing structure or are chute generally indicated at 22. One of the contacts, namely the contact It, has been specifically indicated as a stationary contact which is supported within the arc chute 22 in accordance with a feature of the present invention which will be described hereinafter. The contact 20, on the other hand, is a movable contact which is controlled by the operating mechanism 2| in a manner described below. It will be understood that the engaging portions of the contacts l9 and 25 are preferably formedof an arc-resisting material to prevent freezing of the contacts when they are subjected to currents of such magnitude as to cause them to weld. A suitable arc-resisting material for this purpose is a silver tungsten alloy.

Considering now the operating mechanism generally indicated at 2|, the elements of which are best shown in Fig. 2 of the drawings, it is observed that the operating mechanism 2| is supported by means of a support or frame member 25 which may be fastened to the base III as by means of suitable screws 28 extending through the bottom wall of the base member and threadedly engaging the frame or support 25. If desired, a suitable cover member 21 may be provided'to cover the recesses in which the screws 26 are disposed and the cover 21 may be held in position by suitable pin means 28 or the like. The frame or support 25 for the operating mechanism 2| comprises a pair of parallel upwardly extending leg portions 25a at one end thereof and a pair of parallel upwardly extending leg portions 25b at the other end thereof. Interconnecting the portions 25a and 25b is the portion 25c of the frame or support 25 which comprises a channel-shaped portion within which the current responsive tripping means to be described hereinafter are disposed. The portions 25a, 25b and 25e are all integral and the parallel portions 25a and 251) are each interconnected by a web portion so as effectively to present a channel-shaped construction throughout.

For the purpose of movably supporting the movable contact 20, there is provided a contact carrying element 30 which is pivotally mounted as indicated at 3| to the upwardly extending leg portions 25a of the frame or support 25. As illustrated, the contact carrier 30 comprises a pair of side pieces 30a in the form of quadrants of a circle interconnected by a base portion 30b which is preferably integral with the side portions 30a. The movable contact 20 is preferably supported on a contact supporting rod 32 suitably fastened to the base or web portion 30b of the contact carrier 30a as by means of screws or rivets 23. The other ends of the quadrant-shaped parallel disposed side pieces 30a of the contact carrier 30 are interconnected by a pin member 34. In addition, the contact carrier 30 is provided with integral extensions 35 for receiving a suitable hammer blow or the like from an automatic tripping device to be described hereinafter.

As pointed out above, the switch of the present invention is manually operable through actuation of a suitable handle-l3. Specifically, this handle II, which is preferably formed of insulating material or the like, is'suitably fastened to an actuating member 30 which is pivotally supported tothe upwardly extending legs a of the frame 25 as is indicated at 31. The actuating member is of somewhat U-shaped configuration with the legs of the U "a spaced so as to fit between the upwardly'extendlng legs 25a of the frame or support I! and so as to receive between the legs "a of the U the contact carrier 8.. A suitable pin 39 interconnects the ends of the legs a of the U-shaped actuating member ll. In order to limit the maximum pivotal movement of the actuating member 88, the ends of the U-shaped legs "a are each provided with extensions I which in the open circuit position engage with stop members ll extending inwardly from the legs 25a of the frame 25 and in the closed position of the switch engage the stop members 42 extending inwardly from the legs "a. In Fig. 2 of the drawings where the switch is in the closed position, it is noted that the extensions are in engagement with the stop members 42.

Where an electric switch or circuitbreaker is expected to interrupt currents of considerable magnitude such as short circuit currents, it has been common practice to cause the relatively movable contacts to separate with a snap action, thereby insuring the quick drawing and extinction of an are. It is also customary to have these contacts close the circuit with a snap action to prevent an are being drawn before the contacts are completely closed. Such a snap acting feature of the contacts for both opening and closing of the circuit breaker is obtained merely by interconnecting the pin 34 of the contact carrier 30 with the pin 39 of the actuating member 36 by means of a tension spring 43. With this arrangement, an over-center device is provided operatively relating the actuating element 36 and the contact carrier It). Movement of the actuating member in one direction tends to move one of the supports for the tension spring 43 in an overcenter direction so that relative movement between the contacts under the influence of the tension spring occurs prior to complete movement of the actuating member 36 in the predetermined direction. If the actuating element It is moved in the other direction, the same action occurs except that the contacts move in the opposite manner with a snap action. It should be understood that the particular overcenter device illustrated forms no part of the present invention and any other suitable means for providing snap action operation of the contacts during both the circuit closing and the circuit opening operations may be employed.

In circuit breakers of the type described above, it is also desirable to provide suitable current responsive means which will cause relative separation of the contacts of the circuit breaker in the event that an overload condition persists for a sui'ilcient length of time to cause damage to the associated circuit if it is permitted to continue. Thermal-responsive means in the form of a bimetallic element or the like are commonly used for this purpose and accordingly, there is illustrated in Fig. 2 of the drawings a bimetallic suitable insulating means electrically connected to the terminal ll of the switch in any suitable manner. The free end of the bimetallic element 45 is provided with an upwardly extending latching element 41 which is adapted to-be engaged by a suitable cooperating latching member 4. supported in any suitable manner from a suitable plunger mechanism generally indicated at ll and controlled by the bimetallic element 4!. The free end of the bimetallic strip 45 is electrically connected by one or more parallel conductors MI with the movable contact 20, thereby insuring that the circuit through the electric switch or circuit breaker from terminal I! to the movable contact Iii includes the bimetallic element I and the conductor or conductors N.

For the purpose of insuring high speed relative separation of the contacts I! and 20 in the event of an abnormal circuit condition on the circuit controlled by the circuit breaker of the' present invention, there is provided the plunger mechanism 49 which comprises a cup-shaped or cylindrical plunger member 5| having an upwardly extending yoke Sla integrally formed therewith. A suitable spring in the form of a coiled compression spring 52 contained within the cup-shaped plunger it normally tends to bias the longitudinally movable plunger 5] into striking engagement with the projections 35 of the contact carrier 30. The reciprocating plunger M is supported on a cylindrical member 53 which is nested within the plunger ii. The coiled compression spring 52 is actually contained within the nested cylindrical members 5! and W and tends to bias them into non-telescopic relationship.

The inner supporting cylinder 53 is suitably supported as by means of a screw 54 from the web portion between the upwardly extending portions 25b of. the frame or support 25. When the latch members 41 and 48 are in latching relationship as indicated in Fig. 2 of the drawings, the cylindrical members 5i and 53 of the spring biased plunger mechanism 49 are held in a substantially fully telescoped position with the compression spring 52 held in a charged condition so that upon release of the latching means, the plunger SI of the plunger mechanism 49 is in position to hit the contact carrier 30 or the extensions 35 thereof a hammer blow causing relative separation of the contacts and insuring separation thereof even though the contacts have tended to be frozen together. 7

The yoke or upwardly extending portions Ila of the plunger mechanism generally indicated at 49 are provided in order to engage the actuating member 38. Upon operation of the circuit breaker to the open position in response to an abnormal current condition which causes release of the cooperating latching members 41 and It, the extension or yoke 5ia engages the actuating member 88 so as to move the actuating member to the intermediate position shown in Fig. 3 of the drawings, thus giving a clear indication to the operator that the circuit breaker is not only in the open position but furthermore. that it has been actuated to this position by virtue of an abnormal current condition existing on the controlled circuit. In addition, the extensions or yoke Ma provides a means by which a force may be transmitted from the actuating member It to the plunger mechanism generally indicated at 49. whereby upon moving the handle It from the position indicated in Fig. 3 of the drawings to the position indicated in Fig. 4, the plunger mechanism is relatched and the compression spring 52-is recharged while the contacts of the circuit breaker remain in the open position. As soon as the plunger mechanism has been moved sufficiently from the position shown in Fig. 3 of the drawings to the position shown in Fig. 4 of the drawings, the latch member 48 will be moved into engaging relationship with the cooperating latch member 41 supported on the free end of the bimetallic element 45. It will be understood that the calibration of the bimetallic element and consequently the tripping f the circuit breaker in response to a long-time overload condition on the associated circuit may be controlled by controlling the length of the latch member 41. If desired, suitable adjustable means may be provided or on the other hand, calibration may be obtained by filing the latch member 41 to the desired height to give the desired operating characteristics.

From the above discussion, it will be apparent that if an abnormal current condition exists on the circuit controlled by the circuit breaker oi the present invention for a sufficient length of time to cause the bimetal to deflect in a downward direction to an extent to free cooperating latching member 48, then relative separation of the contacts i9 and 20 will occur. Such operation will require a predetermined delay due to the time involved in heating bimetal 45- to the desired temperature. As was pointed out above, under short circuit conditions, it is essential that X the circuit be interrupted substantially instantaneously. Accordingly, there is provided an additional means for releasing the plunger operated mechanism generally indicated at 48 which aiditional means is also current responsive and has been illustrated as an electromagnetic device generally indicated at 51 comprising a U-shaped magnetic member or core structure 58 and a cooperating movable armature member 59 which is suitably supported from the free end of the bimetal in a position above the legs of the U-shaped core structure 58. The upper-ends of the legs of the U-shaped core structure 58 are cut at an angle as is indicated at 80 so that when the bimetal operates in the manner of a cantilever, the armature 58 will engage the core structure 58 across the entire end surface of the legs thereof. In accordance with a feature of the present invention, the core structure 58 has a magnetomotive force applied thereto by virtue of the fact that the flexible conductor or conductors pass between the legs of the U-shaped core member 58, as is best shown in Fig. 7 of the drawings, beneath the armature 58. It is apparent that the U-shaped core structure 58 and the armature 58 form a magnetic ring or band substantially completely surrounding the flexible conductor 50 except for the airgaps between the ends of the core structure 58 and the armature 58. In the event of the flow of a short circuit current through conductor 50, suflicient flux is produced in the core structure 58 and armature 58 to cause the armature 58 to move into engagement with the ends of the core structure 58, thus closing the airgaps between the two. The downward movement of the armature 58 will pull the free end of the bimetal element 45 downwardly with the resultant release of the cooperating latching members 41 and 48 and the resultant instantaneous opening movement of the circuit breaker in the manner explained above. With this arrangement, the trip mechanism provides a time interval before relative separation of the contacts under overload conditions and a substantially instantaneous trip under short cir-' cuit conditions.

Although the high speed separation of the contacts l9 and 28 by virtue of the snap acting mechanism described above will cause rapid extinguishment of any are drawn between the contacts l8 and 20 under low current conditions, it is essential that this arc be rapidly extinguished under high current conditions as well and regardless of whether the circuit breaker is used to protect alternating current or direct current circuits. In addition and as was pointed out above. the arc extinguishing operation should occur without noise and without any evidence of flame or arc extinguishing gases. For this purpose, the arc chute 22 referred to above is provided as illustrated in the drawings and particularly with formed from a suitable inorganic insulating material such as a Portland cement asbestos compound or the like. Mounted in the upper portion of the arc chute 22 and s pported by the side plates 62 is a magnetic blow-out coil 88, formed of flat strip conducting material with adjacent turns separated by a layer of insulating material, which has one end thereof electrically connected as by means of a conductor 8| with the circuit breaker terminal IS. The other end of the blowout coil 63 comprises a wider portion of conductor which extends substantially around one-half of the blow-out coil and is supported thereby. The side plates 52 may be provided with cutout portions 68 to accommodate the wider portion 5 of the blow-out coil and support the same in position as is clearly shown in Figs. 3, 4 and 5 of the drawings. The end of the blowout coil 63 connected to conductor 84 extends through an opening in one of the side plates 52 and if desired, a suitable extension of this conductor 64 may be provided to extend through an opening 61 in the other side plate to aid in properly supporting the blow-out coil 63 between the side plate 62 of the arc chute 22. Suitable screws 68 are provided to hold the side plates in position.

In accordance with a feature of the present invention, the stationary contact [8 is fastened as by welding or the like to the portion 85 of the blow-out coil 68. It will be understood that the blow-out coil 63 tends to move the arc drawn between contacts l8 and 20 into the are extinguishing portion of the arcchute 22 which. as illustrated in the drawings, is near the base [0. In order to aid in extinguishing the are, a suitable arc splitter or baflle I0 is provided between the side plates 82, which baflle has a configuration of the character shown in Fig. 2 of the drawings which cannot interfere with the free movement of movable contact 20. H desired, the bafile 10 may be formed of gas-emitting insulating material to aid in extinguishing the are drawn. In any event, the are drawn between the contacts l8 and 20 is forced by the blow-out coil 63 into intimate engagement with the baille 10 to cause rapid cooling and de-ionization of the arc gases with resultant rapid extinguishment of the are. In certain cases, it may be desirable to provide suitable inserts or liner members such as 10a shown in Fig. 8 of the drawings formed of gas-emitting insulating material to further cool the are drawn and from which gases are; evolved when. effected.lay-thev heat of arcane.

an electric arc to aid in the arc extinguishing operation. A suitable material for this purpose is horn fiber, methyl methacrylate. or the like.

In view of the detailed description included above. the operation of the circuitbreaker o! the present invention will be understood by those skilled in the art. Briefly, the handle i3 may be moved manually from the positions indicated in Figs. 3. 4 and 5 oi the drawings to open and clme the circuit breaker with the contacts separating and. en aging with a snap action. In the event of an abnormal current condition on the circuit controlled by the circuit breakerof the present invention, the contacts I! and 20 are automatically operated. I! the abnormal current condition is a long-time overload condition. the circuit breaker will be operated to the open position when the bimetal 45 has heated sufllciently to operate'the latching means comprising;

the cooperating latching elements 41 and It whereupon the longitudinallymovable plunger mechanism '48 comprising the plunger ll engages the contact carrier 30 so as to move contact 20 to the open position. It should be noted that by virtue oi the fact that the plunger 50 engages the contact carrier 30 directly connected tothe movable contact 20, trip-free operation of the circuit breaker is permitted. Thus, even when the operator is moving the handle i3 from the position shown in Fig. 4 of the drawings to the position shown in Fig. 2 of the drawings, the circuit breaker can open at high speed regardless of the position of the handle i3. In the event of a short circuit condition, the surge current flowing through the conductor 50 will produce sufllcient flux in the magnetic structure comprising the core 58 and the armature 59 to cause movement oi the armature 59 with the resultant substantially instantaneous opening of the circuit breaker. 'If the circuit breaker is operated to the open position by either the bimetallic element 01 the electromagnetic means described, the extension ila of the plunger mechanism 49 moves the actuating member 38 and the handle it to an intermediate position such as is shown in Fig. 3 of the drawings, whereby the operator is apprised of the fact that the circuit breaker has been operated to the open position in response to an abnormal condition. The operator may then take steps to determine what the abnormal condition was prior to reclosing the circuit breaker ii he so desires. To reclose the breaker when opened automatically in cooperation with one oi the current responsive means, it is necessary first to move the handle II from the intermediate position shown in Fig. 3 of the drawings to the open position shown in Fig. 4 of the drawings to recharge and relatch the plunger operated mechanism 49. whereupon subsequent movement of the actuating member 36 to the closed position will reclose the circuit breaker, with the automatic tripping mechanism conditioned to operate the circuit breaker in the event of an abnormal current condition.

From an examination oi Fig. 2 01' the drawings, for example, it is apparent that opening of the circuit breaker in response to operation of the electromagnetic means requires movement of the armature 59, together with flexing oi' the bimetallic element 45. Under certain conditions, the force required to move the bimetallic element ll 'may be too high i'or satisfactory operation of the electromagnetic tripping device.

.Accordingly, in Fig. 9 oi the drawings, there is mme d et n r s nt en-- tion wherein movement oi the armature II in response to a short circuit condition does not require flexing oi the bimetallic element Ql. The. corresponding parts of Fig. 9 of the drawings are designated by the same reference numerals as in the preceding figures. However, instead of the bimetallic element ll, which is designated as 45 in Fig. 9 of the drawings supporting the armature 59 and the cooperating latching member 41, there is provided an intermediate member 16 in the form 0! a U with one of the legs oi the U having an extension pivotally mounted as indicated at 16. This leg of the U-shaped member 15 supports the latching element 41. The other leg of the U-shaped member I! supports the armature 59 above the core structure II in a manner clearly shown in Fig. 9 oi the drawings. A suitable compression spring 11 is' disposed between the upper surface of the bimetallic element 45' and .the upper leg of the U-shaped member 15. This compression spring I1 is a relatively weak spring serving merely to maintain the pivotally mounted member 15 in the position shown when no force is applied to the armature 59 and no flexing oi the bimetal 45' occurs. -A suitable extension 18 on the lower surface 01' bimetallic element 45' engages the lower leg of the U-shaped member 15. An examination oi Fig. 9 of the drawings will show that the current responsive tripping means operate in the same manner as in the arrangement shown in Fig. 2 oi the drawings except that the electromagnetic tripping device can cause the armature 59 to move downwardly to cause unlatching of the cooperatin latching members 41 and It without substantially deflecting the bimetallic element it merely by compressing weak compression spring 11. On the other hand, deflection or flexing of the bimetallic element 45' will cause the extension 18 thereof to move the U-shaped pivotal member 15 downwardly to unlatch the latching means.

Although the circuit breaker thus far described has been illustrated specifically as a single pole circuit breaker, it will be understood that it may equally well be a multi-pole breaker such as a two phase or three phase circuit breaker. In

certain applications, it is desirable that upon the automatic operation of one pole oi a multi-pole circuit breaker to the open circuit position, the other associated poles of the circuit breaker also be moved to the open circuit position. This can readih be accomplished by utilizing the modification of the present invention illustrated in Figs. 10 and 11 of the drawings. In these flgures there is illustrated a multi-pole circuit breaker 19, each pole of which is substantially identical with the construction "shown in Fig. 9 of the drawings except for the addition 01' an extension on the armature l9 and the provision of a trip bar common to all poles of the circuit breaker. Each armature I8 01 the multi-pole circuit breaker 19 shown in Fig 11 of the drawings is provided with an extension 80. A suitable trip bar llprefer ably formed of molded insulating material is pivotally mounted within the housing defined by the base It and the upper member .01 the multi-pole circuit breaker 19 so as to extend adjacent each of the operating mechanisms II of the separate poles of the multi-pole circuit breaker 19 in the manner shown in Fig. 10 of the drawings and so as to be positioned adjacent the extensions of the armatures 69. Adjacent each pole of the multi-pole breaker, the trip bar tromagnetic means comprising the core structure II and the armature N, the latch member 48 will engale the extension '5' of the associated insert 85, thereby rotating the trip bar 8| in a counterclockwise direction as viewed in Fig. 11 of the drawings. Such counterclockwise rotation of the trip bar 8| will cause the portions 85" of the inserts associated with the poles not actuated to the open position in response to operation of their current responsive means to engage the extensions III of the corresponding armature so causing downward movement thereof and resultant release of all of the latching means. It is thus apparent that a simple and foolproof means is provided for automatically opening all poles of the multi-pole circuit breaker in response to automatic operation of one pole thereof. The corresponding parts of Figs. 10 and 11 are designated by the same reference numerals as in the preceding figures.

The operation of the modification illustrated in Figs. 10 and 11 will be apparent in view of the detailed description included above.

While there have been shown and described certain particular embodiments of the present invention in connection with electric switches or circuit breakers, it is not desired that the invention be limited to the construction shown and described for it will of course be apparent that changes and modifications may be made therein without departing from the present invention, and it is aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the present invention. v

I claim:

1. An electric switch comprising a pair of relatively movable contacts including at least one movable contact operable between an open circuit land a closed circuit position, a pivotally mounted contact carrier for said movable contact. a manually operable actuating element, an over-center device operatively relating said actuating element and said contact carrier for causing said movable contact to move with a snap action from its open circuit to its closed circuit position and from its closed circuit to its open circuit position, a longitudinally movable plunger, means for positioning said plunger ad- Jacent said contact carrier so as to be capable of engaging the same. spring means for biasing said plunger into engagement with said contact carrier, current responsive latch means for restraining said plunger and said spring means associated therewith in a position to strike said carrier and move said movable contact to its open circuit position upon release of said latch means,

and an extension on said plunger engageable by said actuating element for resetting said plunger through movement in a predetermined direction of said actuating element following opening of said switch in response to operation of said current responsive latch means.

2. An electric switch comprising a pair of relatively movable contacts including at least one assarn movable contact operable between an open circuit and a closed circuit position, a movable contactcarrier for supporting said movable contact, a manually operable actuating element, an

over-center device operatively relating said actuating element and said contact carrier for causing said movable contact to move with a snap action from its open circuit to its closed circuit position and from its closedcircult to its open circuit position, a longitudinally movable plunger, means for supporting said plunger in a position capable of being moved to engage -said contact carrier, spring means associated with said plunger for biasing said plunger into engagement with said contact carrier, latching means for holding said plunger out of contact with said contact carrier and for maintaining said spring means in a charged condition, and current responsive means for releasing said latching means to cause said plunger to strike said contact carrier and move said movable contact supported thereby to the open circuit position even though said actuating element is prevented from moving to a corresponding position.

3. An electric switch comprising a pair of relatively movablecontacts including at least one movable contact operable between an open circuit and a closed circuit position. a frame memberfa contact carrier pivotally mounted to said frame member, means for supporting said one movable contact from said contact carrier, a manually operable actuating element pivotally supported on said frame member, an over-center device operatively relating said actuating element and said contact carrier for causing said movable contact to move with a snap action from its open circuit to its closed circuit position and I from its closed circuit to its open circuit position, an energy storage mechanism comprising a longitudinally movable plunger, means for supporting said plunger in a position capable of being moved by energy stored in said energy storage mechanism into engagement with said contact carrier to strike the contact carrier and move said movable contact to the open circuit position, latching means for restraining said energy I storage mechanism in a charged condition, means responsive to a. predetermined abnormal current 50 condition on the circuit controlled by said switch for substantially instantaneously releasing said latching means permitting said energy storage mechanism to cause high speed opening of said switch even though said actuating element is prevented from moving to a corresponding position and additionalmeans associated with said energy storage mechanism engageable by said actuating element whereby said energy storage mechanism may be recharged by subsequent movement of said actuating element.

4. An electric switch comprising a pair of relatively movable contacts including at least one movable contact operable between an open circuit and a closed circuit position, a movable contact carrier. for supporting said movable contact, a manually operable actuating element, an over-center device operatively relating said actuating element and said contact carrier for causing said movable contact to move with a snap action from its open circuit to its closed circuit position, a longitudinally movable plunger, means for supporting said plunger in a position capable of being moved to engage said contact carrier, spring means associated with said plunger for 75 biasing said plunger into engagement with said a',ses,174

contact carrier, latching means for holding said plunger out oi contact with said contact carrier and for maintaining said spring means in a chargedcon'dition, thermal means for releasing said latching means to cause said plunger to strike said contact carrier and move said movable contact supported thereby to the open circuit position even though said actuating element is prevented from moving to a corresponding position, and electro-respons ive means for substantially instantaneously releasing said latching means upon the flow of short circuit current through said switch.

I '5. An electric switch comprising apair of relatively movable contacts including at least one movable contact operable between an open circuit and a closed circuit position, a movable contact carrier for supporting said movable contact, a manually operable actuating element, an over-center device including a tension spring operatively relating said actuating element and said contact carrier for causing said movable contact to move with a snap action from its open circuit to its closed circuit position and from its closed circuit to its open circuit position, a longitudinally movable plunger, means for supporting said plunger in a position capable oi being moved to engage said contact carrier, spring means associated with said plunger for biasing said plunger into engagement with said contact carrier, latching means for holding said plunger out of contact with said contact carrier and for maintaining said spring means in a charged condition, and current responsive means for releasing said latching means to cause said plunger to strike said contact carrier and move said movable contact supported thereby to the open circuit position even though said actuating element is prevented irom moving to a corresponding position comprising a bimetallic element and an electromagnetic element, either of said elements being capable oi releasing said latching means depending upon the type of abnormal current condition existing on the circuit controlled by said switch.

6. An electric switch comprising a pair of relatively movable contacts including at least one movable contact operable between an open circuit and a closed circuit position, a frame memher, a contact carrier pivotally mounted to said frame member, means for supporting said one movable contact from said contact carrier, a

manually operable actuating element pivotally supported on said frame member, an over-center device operatively relating said actuating element and said contact carrier for causing said movable contact to move with a snap action from its open circuit to its closed circuit position and from its closed circuit to its open circuit position,

cooperating stop members on said frame member and actuating element to limit the pivotal movement in either direction of said actuating element, an energy storage mechanism comprising a longitudinally movable plunger, means for supporting said plunger in a position capable of 'by said switch for substantially instantaneously releasing said latching means permitting said energy storage mechanism to cause high speed opening oi said switch even though said actuating Ill element is prevented from moving to a corresponding position, and means associated with said energy storage mechanism engageable by said actuating element whereby said energy stora e mechanism may be recharged by subsequent movement of said actuating element. s

'1 An electric switch comprisinga pair of relatively movable contacts including at least one movable contact operable between an open circuit and a closed circuit position, a support, a U-shaped manually operable actuating element pivotally mounted to said support, a movable contact carrier for supporting said movable con tact disposed between the legs of said U-shaped actuating element and pivotally mounted to said support, an over-center device including a tension spring operatively relating said actuating element and said contact carrier for causing said movable contact to move with a snap action from its open circuit to its closed circuit position and from its closed circuit to its open circuit position, a longitudinally movable plunger, means for supporting said plunger in a position capable of being moved to engage said contact carrienspring means associated with said plunger for biasing said plunger into engagement with said contact carrier, latching means for holding said plunger out of contact with said contact carrier and for maintaining said spring means in a charged condition, and current responsivemeans ior releasing said latching means to cause said plunger to strike said contact carrier and move said movable contact supported thereby to the open circuit position even though said actuating element is prevented from moving to a corresponding position.

8. An electric switch comprising a terminal, a

pair of relatively movable contacts including at least one movable contact operable between an open circuit and a closed circuit position, a support, a manually operable actuating element pivotally mounted to said support, a movable contact carrier for supporting said movable contact pivotally mounted to said support, an over-center device including a tension spring operatively relating said actuating element and said contact with said contact carrier and for maintaining said spring means in a charged condition, electromagnetic means for releasing said latching means i to cause said plunger to strike said contact carrier comprising a magnetic loop formed of a U-shaped member and an associated armature movable relative to said U-shaped member, and a flexible conductor extending through said magnetic loop interconnecting one of said contacts and said terminal so that a short circuit current flowing through said flexible conductor causes high speed operation or said electromagnetic means to release said latching means.

9. The combination set forth in claim 2 in which said current responsive means comprises a bimetallic element and an electromagnetic element, said electromagentic element when eil'ective causing release of said latching means without aflecting said bimetallic element.

10. The combination set forth in claim 2 in 15 which said current r sponsive means comprises a bimetallic element and an electromagnetic element, and in which said latching means comprises a pivotally mounted element, said himetallic element having a fixed end and a movable end, said bimetallic element and said electromagnetic element both bingcapable oi causing pivotal movement of said pivotally mounted element, said electromagnetic element when eiiective causing pivotal movement of said pivotally mounted element without aflecting said bimetallic .element, and compression spring means interposed between the movable end of said bimetallic element and said pivotally mounted element for normally holding said pivotally mounted element in a predetermined position.

11. The combination set forth in claim 2 in which said current responsive means comprises a bimetallic element and an electromagnetic element, and in which said latching means comprises a ivotally mounted element, said bimetallic element having a iixed end and a movablev asaarn the poles of said switch and including a first and second extension adjacent each pole thereof, means responsive to the release of the latching means associated with any pole of said switch for engaging the associated first extension to rotate said trip bar, and means responsive to rotation 01' said trip bar for causing the second extensions on said trip bar to release the latching means 01 all the other poles of said switch.

LESTER C. HART.

REFERENCES CITED The following references are 01' record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,641,202 .Ruppel Sept. 6, 1927 1,683,132 Hall Sept. 4, 1928 1,809,275 Jennings June 9, 1931 2,027,238 Lindstrom Jan. 7, 1936 2,089,716 Smith Aug. 10, 1937 2,175,859 Tusing Oct. 10, 1939 2,184,372 -Von Hoorn Dec. 26, 1939 2,200,108 Wilckens May 7, 1940 2,325,717 Swingle Aug. 3, 1943 2,328,458 Jackson et al. Aug. 31, 1943 2,342,945 Krieger Feb. 29, 1944 2,356,039 Ellis et al. Aug. 15, 1944 2,416,163 Dyer et al. Feb. 18, 1947 2,419,125 Doriman et a1 Apr. 15, 1947 2,439,511 Green Apr. 13, 1948 2,443,090 Wise June 8, 1948 

